Helicobacter pylori, an organism that colonizes the mucus gel layer of the gastric antrum, is associated with recurrent peptic ulcer disease and gastric malignancies. One of the preferred methods for diagnosis of H. pylori infection is the 13CO2-urea breath test. This non-invasive test is both sensitive and specific, but currently requires equipment that is costly and difficult to maintain. An analysis system based on infrared absorption spectroscopy is proposed in place of isotope ratio mass spectrometry for the analysis of breath 13CO2/13CO2 ratios as part of the 13C-urea breath test. Advantages of this system over conventional mass spectrometry analysis include substantially reduced equipment and maintenance costs, as well as greatly simplified measurement and sample preparation procedures. The proposed system incorporates a novel infrared sample cell for obtaining high signal/noise. Based on the preliminary results, we plan to develop a commercial instrument that should make the 13C-urea breath test, as well as other breath tests utilizing 13CO2/13CO2 ratio analysis, accessible to a wide range of medical laboratories, physician offices, and clinics. This improved instrument should in turn lead to substantial reductions in medical costs and analysis turn-around time associated with H. pylori testing or other testing employing 13CO2 analysis. PROPOSED COMMERCIAL APPLICATION: The infrared spectral analysis system for H. pylori detection proposed in this program would lead to an inexpensive, safe, and reliable commercial instrument easily used in small and large medical laboratories and physician offices. This instrument would also allow diagnosis of a variety of other types of digestive disorders for which 13C breath tests are used and could be employed in underdeveloped countries in H. pylori eradication programs.